Various medical and therapeutic procedures require the patient to lie in a prone position—that is, to lie on his/her front, facing downwards. In particular, a range of surgical procedures including for example certain forms of spinal surgery require this mode of patient presentation. If the patient were simply supported on a flat bed, the head would naturally be turned to one side or the other but this is not desirable. Among other unwelcome effects, it puts the cervical spine in an abnormal position and potentially constricts the trachea and larynx.
It is known instead to provide a shaped head support upon which the prone patient's face rests. The support can maintain the head in a generally upright orientation. That is to say that the plane of symmetry of the head is roughly vertical. The support is shaped to engage with selected regions of the face and to generally conform to the face's shape in these regions, tending to avoid local pressure concentration. Compliant foam may form the parts of the support on which the face rests.
The shape of some known head supports provides cut-ways in regions corresponding to the patient's nose and mouth, leaving the airways clear. The cut-aways also typically extend to the region of the patient's eyes to prevent pressure from being applied to them. Sustained pressure to the eyeball can otherwise cause serious injury to the visual system.
Head supports may comprise a generally rigid frame with a shaped foam insert. In other instances, a unitary body of foam forms the entire support, and may for example have a flat under-surface to rest on an operating table.
During surgery, the anaesthetist and others may need to observe the patient's face. Of course, a portion of the face is in contact with the support, but various known head supports provide for observation of the eye, nose and mouth region (which are left clear by the aforementioned cut-aways) being shaped to provide a line of sight from the outside of the support to these parts of the face. In certain known one-piece foam head supports, this is achieved by cutting away regions of the support on either side of the face to form downwardly open viewing channels. Such a support may be placed upon an upwardly facing mirror, so that the reflection of the face can be viewed from above in the mirror, through the viewing channels. But the viewing channels can create a problem in that they impair the rigidity of the head support, which may consequently bend in use in a manner which impairs its function. Bending can lead to loss of control of head orientation and to undesirable local pressure concentration.
Head supports for use in surgery may need to provide a route for one or more conduits to be led to the mouth and/or nose of the patient. Specifically, provision typically needs to be made for routing of an endotracheal tube. Other forms of conduit may additionally or alternatively be required, such as nasogastric tubes. The term “conduit” as used herein should be understood broadly to encompass any form of elongate member to be led to the patient's face. Consideration needs to be given to the process by which the conduit is to be introduced to the head support, since it is often the case that neither end of the conduit is free to be longitudinally fed into the head support, e.g. because the patient is already intubated when placed upon the operating table. An upwardly open channel leading from the periphery of the support to the region of the nose/mouth may be formed in the head support to receive the conduit or member. This makes it straightforward to introduce the conduit but can create a different problem since regions of foam material adjacent the channel are deprived of support by it and may deform excessively, impairing the support function. For instance, a region of the support lying beneath the patient's chin may collapse toward the channel, causing control of the orientation of the patient's head to be impaired. Other known head supports provide a downwardly open channel for the same purpose, but this too can undesirably impair rigidity of the head support and introduction of the endotracheal tube in this case requires access to the underside of the head support (e.g. by lifting it from the table) which is less convenient.
U.S. Pat. No. 5,269,035 (Hartunian) discloses a head support whose shape is generally cubic but has first and second “arcuate-shaped cavities” formed in its upper surface, one to support the patient's forehead and one to support the chin. Between these cavities is an opening through which the face of the patient is visible. A downwardly open, laterally extending channel of the type mentioned above provides a route for an endotracheal tube.
U.S. Pat. No. 4,757,983 (Ray et al.) discloses a head and chin rest for use in surgical operations. There are several embodiments but in each, cushions of the head and chin rests are separately formed and are physically separated, giving access to, and visibility of, much of the patient's face. The separation of the supports is adjustable. This necessitates a relatively elaborate rigid support structure for the cushions.
U.S. Pat. No. 4,752,064 (Voss) discloses a generally cuboidal pillow with a T-shaped void in its upper surface to accommodate the mouth, nose and eyes. Channels formed in the pillow's under-surface can be used to accommodate an endotracheal tube. These channels are shown to be downwardly open.
U.S. Pat. No. 5,613,501 (Michelson) discloses a face support which has a concave curved upper surface to contact the face and which also has a concave lower surface, so that the support deforms under the weight applied to it in use, tending to cause it to press on the sides of the patient's face. This prior art document illustrates the provision of an upwardly open channel for an endotracheal tube, which is considered to give rise to the potential problem of undesirable deformation of the support's shape in use which are discussed above.
U.S. Pat. No. 3,337,883 (Allison) discloses a head rest having a trough-shaped body of plastics sheet material carrying a resilient cushioning pad, both being cut away to accommodate the eyes, nose and mouth. What rigidity this structure has appears to be contributed by the plastics body.
U.S. Pat. No. 3,694,831 (Treace) discloses a multi-purpose medical head support having a base portion and a pair of wedge-shaped pads fixedly mounted on the base portion. No provision appears to be made for an endotracheal tube or for observation of the patient's face.